Today OnStar, a GM company focused on in-car communication and security, announced what it calls an API. Though not yet released, nor totally open and perhaps not even an API, the move is certainly part of "car as a platform." Building apps for cars is a movement that hasn't seen much progress since Ford's announcement two years ago. Though there is still a lot of potential, especially with the car culture in much of the US, some have questioned whether safety will stifle in-car apps.
MapAnything describes itself as a Location of Things company. Recently, the company introduced a suite of APIs that provide programmatic access to its routing and optimization engines. The company is specifically focused on fleets and routing B2B companies, and plans to introduce more APIs soon.